The long-term goals of this training award are to prepare the applicant for a research career in the area of Pediatric Low Vision. Advanced training in the areas of infant vision and human electrophysiology will enable the applicant to develop new and more effective diagnosis and treatment regimes for infants with blinding eye disorders. Understanding the mechanisms of visual loss and recovery in infancy requires an understanding of human developmental critical periods for different visual functions and an ability to measure visual function accurately during early infancy and childhood. This award will provide the applicant with training in these areas that will supplement his clinical expertise. It will also provide the applicant with a large database that can be used in future, independent research. Human amblyopia will be used as a model system to study human developmental critical periods and cortical plasticity. The research is focused on determining the patterns of visual loss that occur in infants and children with amblyopia, prior to treatment. The data will be used to test the hypothesis that the amblyopic visual system is always equivalent to that of the normal visual system at an earlier stage of development. The first Aim will validate new Visual Evoked Potential (VEP) measures of two visual functions with differing developmental sequences -- grating acuity and vernier acuity. The second Aim will measure developmental sequences for grating acuity and vernier acuity using the sweep VEP measures developed in Aim 1. The third Aim will apply the new VEP measures in patients when first diagnosed with amblyopia. Loss patterns in the amblyopic patients will be compared to normative values measured at different developmental stages. Does amblyopia result in a simple arrest of each of the two visual functions? Knowing the loss relative to normals on one variable, can one predict the loss on the other variable from knowledge of normal growth patterns? The patterns of functional loss will be correlated with age of diagnosis and cause of the amblyopia (strabismus, anisometropia or both). Do strabismus and anisometropia affect different visual functions differentially? Is the combination of risk-factors more amblyogenic?